SCIENCE-GOSSIP. 



171 



the water has retired. If we wait for a quarter or 

 half an hour after this time, we shall, I think, be 

 well on the safe side, though perhaps a watch 

 ought to be kept during this time to see that no 

 castings are obliterated by waves. For the same 

 reason we should avoid a day when the sea is 

 rough, for even if the castings are not entirely 

 washed away they may be much reduced in size if 

 surrounded again by water. 



To show how the measurements should be 

 reduced, I will take one of those I made at Holy 

 Island. The following are the notes : " August 18th, 

 1891, Holy Island sands, about one hundred yards 

 west of the old lime-kilns. Sides of triangle, 

 115, 119J and I2QJ- inches. Number of castings, 53. 

 Number collected, 6. Castings all large, and of 

 nearly uniform size." 



We have first to find the area of the triangle. 

 This is done as follows : Add the three lengths 

 together and divide the sum by 2, giving 182. 

 Subtract the length of each side in turn frcm 182 ; 

 the remainders are 67, 623 and 52J. Multiply 182, 

 67, 62f and 52J together ; the product is approxi- 

 mately 39,986,687. Find the square root of this 

 number, namely, 6,324. This gives the area of the 

 triangle in square inches. The rest of the calcula- 

 tion is simple rule-of-three. If there are 53 

 castings in an area of 6,324 square inches, we 

 easily find the equivalent number to be 52,568 per 

 acre. 



The six castings collected were taken home, dried 

 in an oven, and were found then to weigh 7,986 

 grains. By rule-of-three again, we find the weight 

 of 52,568 castings to be 419,808,048 grains, or about 

 9.995 pounds. Since there are 705 high tides in a 



year, it follows that, if the same amount were 

 thrown up at every tide, the lobworms eject 

 annually on the surface as much as 3,146 tons of 

 sand per acre. In this particular case the castings, 

 though much larger than usual, were not nearly 

 so numerous as in other parts. Taking all my 

 observations on the Holy Island sands, the average 

 number of castings is 82,423 per acre, or more than 

 fifty million per square mile; and the average 

 weight of sand brought up annually to the surface 

 is 1,911 tons per acre. Whether the number and 

 weight of castings thrown up may be regarded as 

 uniform throughout the year, I am unable to say. 

 I have never been in Holy Island during the winter 

 months. At the beginning of this year, however, 

 on the sands a mile or two north of Sunderland, I 

 counted 153 small castings in a triangular area of 

 10,944 square inches, equal to 87,509 per acre. 

 The previous night had been intensely cold, and 

 the sea-water left higher up on the beach was a 

 sheet of ice. The activity of lobworms in winter 

 is therefore evident ; but it appears to me very 

 desirable that further observations should be made, 

 not only at different parts of the coast, but, in one 

 place at least, at regular intervals throughout the 

 year. 



The labour involved in such operations is small 

 in comparison with the interest of the results. I 

 would suggest that measurements should be made 

 once a month, on about the same day of the month, 

 and that on each occasion castings should be 

 collected from three or four neighbouring areas, 

 the same spots if possible, being selected every 

 time. 



373, Gillott Road, Birmingham ; August 5//1, 1895. 



IRREGULARITY OF SOME COTYLEDONS. 

 By H. B. Guppy, M.B. 



A NOTE on tricotyledonous ivy seedlings in 

 Science-Gossip for last May [ante p. So), 

 has tempted me to send the following communica- 

 tion on the subject. Whilst observing the germina- 

 tion of a large number of British plants during the 

 last four years, my attention has been frequently 

 drawn to this matter ; and most of the results 

 obtained are given in the appended table and are 

 illustrated in the accompanying figures. 



These abnormalities constituted, as a rule, a 

 proportion of from two to six per cent, of the 

 seedlings examined ; and, since it was to the 

 twelve plants below named that my inquiries in 

 this direction were mostly confined, such ab- 

 normalities are doubtless just as frequent in the 

 case of many other plants. Sometimes the pro- 



portion may be much greater, as in the 

 instance of Myriophyllum spicatum, where about 

 one-sixth, or seventeen per cent., of the seedlings 

 were thus characterised. As shown in the table, 

 the most frequent type of abnormality was that of 

 seedlings with three cotyledons. Occasionally, as 

 with Caltha palustris and Lysimachia vulgaris, one of 

 the blades of a dicDtyledonous seedling was cleft. 

 Very rarely, four cotyledons were to be observed ; 

 this was remarked in a solitary instance where a 

 seedling of Caltha palustris exhibited two pairs of 

 cotyledons, each pair arising from a common 

 pedicle. The character of the venation sometimes 

 threw light upon the nature of these abnormalities; 

 and it could be thus seen that the supernumerary 

 cotyledons resembled the others, and that the cleft 

 2 



